condensation in electrical box

[casmurbax]

Good day,

I have been working out in my newly built garage the past couple of weeks and while doing so I have been running a propane heater, outside temps have been below 20 Fahrenheit if not colder. The garage is 432 sq ft with a 8 foot ceiling. The walls and ceiling are insulated and sheetrocked.

While I am out there working, a window is open to allow fresh air in and the heater is running about 15%-25% of its capacity if that. I turn it down when it gets to warm so its not running the entire time I am out there. Though I am using a stand alone propane heater currently it is not something that I plan on using after this winter, I will have a permanent heater installed by next winter .

My electrical panel is placed in between 2 studs and insulated from the top, bottom and sides but is placed against the inside of the outside sheathing. I have a 2 inch and 1 inch conduit that come from the outside of the building, through a LBL and run 24 ft above the insulation in the ceiling and then down about 2.5 feet in the insulated wall to the panel.

While working out there yesterday, I noticed that the cover was damp. I disconnected the power to the panel, popped the cover off and noticed that there was moisture inside the panel.

I believe the condensation is coming from the cold air in the conduit hitting the warm air from the garage and the ambient temperature change condensation is being created. I also believe that running the propane heater is contributing to the moisture in the panel as well.

My questions are: How can I stop the condensation from happening?
Is the propane heater a major contributor to my issue? Should I use duct seal to plug up the ends of the conduit in the LBL's on the outside of the garage? Should I plug the PVC on the inside of the panel? Should I pull the electrical panel away more from the outside wall? I don't believe it is actually touching the outside wall, but it is not insulated behind it at all.

NEC code 300.7 states:

Raceways Exposed to Different Temperatures.
(A) Sealing. Where portions of a raceway or sleeve are known to be subjected to different temperatures, and where condensation is known to be a problem, as in cold storage areas of buildings or where passing from the interior to the exterior of a building, the raceway or sleeve shall be filled with an approved material to prevent the circulation of warm air to a colder section of the raceway or sleeve. An explosion proof seal shall not be required for this purpose.

Is duct seal appropriate to use? Should both ends of the PVC be plugged?

Before insulation and sheetrocked.


I am heating with this type of a heater.


Sorry for such a long post. Hopefully I posted it under the right forum, if not please feel free to move it.

Thank you in advance for any help.

 

[PoorOwner]

I would think it's the propane heater, they put tons of moisture in the air, so when the air hits something cool, usually metal surfaces, (can be after you shut off and leave the shop), the dew forms.

 

[mm08822]

Not exactly clear on the LB's and conduit run description. If you mean the LB's are right the point of entry into the building, I would put duct seal into the conduit entering the building. That should stop any cold air flow thru the conduit.

Also need the neutral conductor identified white at both ends.

 

[casmurbax]

Not exactly clear on the LB's and conduit run description. If you mean the LB's are right the point of entry into the building, I would put duct seal into the conduit entering the building. That should stop any cold air flow thru the conduit.

Also need the neutral conductor identified white at both ends.

Yes you are correct on the point of entry.

Good eye on the neutral wire, that picture didn't show it, but it does have a white tracer.



PoorOwner, appreciate your reply as well and it makes sense. I didn't think of how much it gives off the moisture, especially because it does not exhaust outside.

 

[Lonnies Performance]

I have a similar issue... Running a 150,000 btu torpedo heater & I'm getting a ton of condensation also. I have my electrical box open as I'm currently doing my wiring. I could see the moisture on the electrical entrance wiring & a slight fogging of the panel itself.

Currently I heat the building when I'm working & then open all doors to get a heavy breeze through the building for about 15 minutes when I'm done for the night to let the moisture escape. It helps a lot in keeping the humidity lower.

 

[u3b3rg33k]

running a vented heater (exhaust vents outdoors) will solve your condensation problem.

 

[Bert_]

Even with a vented heater this is going to be a chronic problem with no insulation behind that panel. Panel will be cold and if the warm air inside has ANY moisture it will condense on the panel. You need to get some insulation behind it, some thin foam board usually works.

 

[Dagny]

I use to put a 50 watt 240 volt light bulb in the bottom of panels that had little insulation behind them and hook it to 120 volts. This makes them last a very long time.

 

[casmurbax]

Thank you all for replies. I had the propane heater already and the plan was to use it to get through the the rest of the winter.

My brother is going to let me use his TPI HF685TC heater for the time being. I have plans on installing a permanent ceiling unit during the summer.

I am going to pull the panel out and install a foam board behind it along with plugging the LB's where they enter the building.

 

[wyliesdiesels]

Duct seal in the LBs and insulation behind the panels should fix that.

Is this in a detached structure? If so, do you have grounding electrodes connected to the panel? I dont see a GEC on the subpanel...

 

[casmurbax]

Hi wyliesdiesels, Thanks for your reply. That is my plan to do, duct seal and insulate behind the panel.

Yes it is detached garage, the wire run is 185 feet.

As far as the grounding electrode conductor (GEC), I did ask the inspector when he inspected for the rough in if one is needed and I was told no.

There is a GEC connected in the main panel. The panel in the detached garage is not bonded. Should I install one? I still have to have final inspection done.

Thank you.

 

[u3b3rg33k]

Hi wyliesdiesels, Thanks for your reply. That is my plan to do, duct seal and insulate behind the panel.

Yes it is detached garage, the wire run is 185 feet.

As far as the grounding electrode conductor (GEC), I did ask the inspector when he inspected for the rough in if one is needed and I was told no.

There is a GEC connected in the main panel. The panel in the detached garage is not bonded. Should I install one? I still have to have final inspection done.

Thank you.

My understanding this is that ONLY the main panel has the neutral bonded to the ground - all sub panels have four wires run - L1, L2, N, and G. N & G are NEVER bonded in the sub panels.

 

[wyliesdiesels]

Hi wyliesdiesels, Thanks for your reply. That is my plan to do, duct seal and insulate behind the panel.

Yes it is detached garage, the wire run is 185 feet.

As far as the grounding electrode conductor (GEC), I did ask the inspector when he inspected for the rough in if one is needed and I was told no.

There is a GEC connected in the main panel. The panel in the detached garage is not bonded. Should I install one? I still have to have final inspection done.

Thank you.

Detached structures are REQUIRED to have grounding electrodes- either 2 rods or a UFER.

You should have 4-wires feeding the sub as well as a GEC going to rods.

The grounding wire in the feeder going to the main is not a GEC its an EGC equipment grounding conductor.

And thats correct with the bonding on the subpanel. The neutral bar should be isolated and NOT bonded to the enclosure or equipment grounding bar.

 

[casmurbax]

Thanks wyliesdiesels

Well it is a little late for the UFER now, be a little hard to tie that into the wire mesh in the now poured slab.

The 2 rods, is there where I need to pound in 2 8ft rods 6 feet a part and run a wire to the the ground side of the sub panel? (only guessing on these, and yes I know guessing on electrical wiring is not good, that is why I am asking).

I can't believe the inspector didn't say anything, even after I specifically asked him this..... But reading other threads I should have known better.

Thanks

 

[wyliesdiesels]

Inspectors miss things all the time. Doesnt surprise me.

Is he specifically an electrical inspector? Or a general?

 

[casmurbax]

specifically an electrical inspector.

I appreciate you pointing out the error. Now I need to rectify it.

Thank you all.

 

[ishiboo]

I believe the condensation is coming from the cold air in the conduit hitting the warm air from the garage and the ambient temperature change condensation is being created. I also believe that running the propane heater is contributing to the moisture in the panel as well.

Condensation comes from when warm, moist air hits something cold... not the way you are thinking.

Absolutely the propane heater is the source of the issue... it puts 100% of its combustion moisture into the air, making it damp. When it hits the cold panel, the water condenses.

 

[Orionrising]

I believe propane combustion creates about a gallon of water per gallon of propane. I would use a dehumidifier. Also depending on the age of your slab and if its sealed it will put humidity in the air for a while

 

[ard]

The walls and ceiling are insulated and sheetrocked.
.

Personally, if the walls are sheetrocked, Id not rip the panel out to insulate behind....

Id just take care of the heater and get a proper, vented heater for the space....

 

[casmurbax]

Thanks for the replies.

Well I need to cut some sheetrock out anyways, I need to take care of the GEC, while I do that I can insulate behind the panel.

John